Ultrastructural organization of the surface epithelium of gastric mucosa in vitamin A deficiency

Under conditions of experimental A-avitaminosis in cells of superficial epithelium of the chicken stomach mucous membrane certain ultrastructural changes of cytoplasmic membranes takes place. Amount of transport vesicles decreases, regeneration of membranes in the Golgi complex cisterns, secretory vesicles and apical part of the external cellular membrane with development of apical erosions is disturbed. The problem on influence of the changes mentioned to the process of mucus formation, in particular to protein glycosylation in the Golgi complex is discussed. Insufficient vitamin A amount, getting into the organism results in a decreased resistivity of the stomach mucous membrane as a consequence of disturbances in processes of mucus formation and in safety of the apical part of the external cellular membrane of the superficial epithelium.     

The gastric mucosa of the human fetus. I. The surface epithelium

The ontogenesis of the surface epithelium in the gastric mucosa was studied by means of light and electron microscopy in 41 human foetuses ranging from 7th to 12th week of gestational age. The results obtained can be summarized as follows: 1) At the 7th week the gastric mucosa shows a simple pseudostratified epithelium; the epithelial cells are undifferentiated and filled, with glycogen clusters. 2) From the 8th week the epithelial surface shows small depressions that become deeper in the mesenchyme making the first bud of the gastric foveolae. 3) At the 9-10th week the gastric foveolae are more developed. The cells of the gastric epithelium can be therefore separated in two populations: a) the cells of the foveolae; b) the cell of the mucosal surfaces. 4) At the 12th week the cells of the mucosal surface become, on the basis of their histochemical and ultrastructural characteristics, surface mucous cells. The morphological differentiation is testified mainly by the transposition of the nuclei in the basal parts of the cells and by the gradual substitution of the cytoplasmic glycogen by mucous granules.     

Histochemistry of mouse cervical epithelium during chemical carcinogenesis

Synopsis Histochemical investigations have been made on cryostat sections of mouse cervix implanted with either a beeswax-impregnated thread (control) or a 20-methylcholanthrene-impregnated thread in one of the cervical canals. New squamous epithelium (epidermization) and squamous carcinomas were observed in approximately 100% and 50% of the cases respectively, after 4–6 weeks. The 6-week animals showed more advanced tumours compared with the animals killed after 4 weeks. The glycogen staining of the cervical canals treated with beeswax- or methylcholanthrene-impregnated thread was greatly enhanced compared with the untreated control cervical canal. The activity of glycogen synthetase, phosphorylase and lactic dehydrogenase was enhanced in the treated part of the cervix. On the other hand, the activity of acid phosphatase and simple esterase was diminished in the cervical canal treated with beeswax- or methylcholanthrene-impregnated thread. Some other enzymes did not show any changes. Alkaline phosphatase preparations, however, showed significant reduction in the enzyme activity in the carcinogen-treated cervical canal compared with either the untreated or the beeswax-treated canal, an effect which could be specifically attributed to the effect of the carcinogen.     

The vaginal surface epithelium during postnatal development in gerbils

The postnatal development of the gerbil vagina has been investigated and special attention has been paid to the luminal surface epithelium structures. Different types of microvilli and solitary cilia are discussed.     

Cytodifferentiation of the epithelium of the gastric mucosa glands of rats in ontogenesis

Structure of epithelium in the mucous membrane glands of the rat stomach has been studied electron microscopically during embryonal and postnatal periods of development. Time of initial appearance of various types of cells in early stages of the gastric epithelium histogenesis has been verified. Asynchronity of their appearance is demonstrated. In epithelium of the gastric glands in 20-day-old rat embryos poorly differentiated exocrine and also endocrine D- and G-cells are revealed. On the 1st day EC-, ECl-, and on the 3d day--X-endocrinocytes appear. Neighbouring exocrinocytes connect with each other by means of both nonspecific and specific intercellular contacts. Exocrine and endocrine cells connect by means of desmosomes. For the animals of each age group certain range of ultrastructural organization in variously differentiated glandulocytes (they are morphological basis of the reactive changes) is specific.     

Phagocytosis of cells in the gastric surface epithelium of the rat

Summary Gastric surface epithelial cells (SEC) from fed rats, from rats fasted for 16 h and from mucosae exposed in an ex-vivo chamber to 16 mM aspirin for 5 min were examined by transmission electron microscopy. SEC have the capability to phagocytose adjacent epithelial cells and parietal cells. Phagocytosis is rare in mucosae from fasted animals but common in fed animals or after brief exposure to aspirin. Phagocytic capabilities are not restricted to the progenitor zone but exist throughout the surface epithelium. Phagocytosis may provide a mechanism for the removal of damaged or senescent cells from the surface epithelium.Suported by the Medical Research Council of Canada     

Fluorescent derivatization of polysaccharides and carbohydrate-containing biopolymers for measurement of enzyme activities in complex media

Fluorescence derivatization provides a means of tracing the dynamics of polysaccharides even in the presence of high concentrations of other organic compounds or salts. A method of labeling polysaccharides with fluoresceinamine was extended to polysaccharides of a wide range of chemical composition, and alternative means of preparation were established for polysaccharides not initially amenable to column chromatography. The polysaccharides were activated with cyanogen bromide, coupled to fluoresceinamine, and separated from unreacted fluorophore via gel filtration chromatography or dialysis. Since the resulting derivatized polysaccharides proved to be stable to further physical and chemical manipulation, methods were also developed for re-activation and labeling with a second fluorophore, as well as for tethering the labeled polysaccharides to agarose beads. As an example of the application of this approach, five distinct fluorescently-labeled polysaccharides (pullulan, laminarin, xylan, chondroitin sulfate, and alginic acid) were used to investigate the activities and structural specificities of extracellular enzymes produced in situ by marine microbial communities, providing a means of measuring specifically the activities of endo-acting extracellular enzymes and avoiding use of low molecular mass substrate proxies. These labeled polysaccharides could be used to explore the dynamics of polysaccharides in other types of complex media, as well as to investigate the activities and specificities of endo-acting enzymes in other systems.     

Histochemical findings in the rat gastric mucosa during starvation

Summary The influence of starving on the activity of enzymes of the rat gastric mucosa was investigated by selected histochemical methods. Beside the conventional methods of enzymatic histochemistry the technique of semipermeable membranes was used in the proof of lysosomal enzymes. Dehydrogenases were proved in aqueous and also in gel media with PMS.During the starvation in the parietal cells a marked increase took place in the activity of acid phosphatase, E-600 resistant esterase, less in -glucuronidase. High activity of the lysosomal enzymes in macrophages did not change during starvation. Nor did any changes took place in the activity of alkaline phosphatase in the endothelium of the capillaries. The chief cells in the control and starving animals, in contrast to the human gastric mucosa, did not contain any non-specific esterase. Concerning dehydrogenase, parietal cells with a different activity of these enzymes were observed both in starved and control animals.In the rat gastric mucosa starving induced changes in the activity of the enzymes which mark important organelles of the cells. Thus it is possible to consider the observed histochemical changes as a functional manifestation of morphological damage of cellular structures which are affected during starvation.     

Histochemistry of mucosubstances in the gallbladder epithelium of the chick embryo

Summary Mucosubstances of epithelial cells of the chick embryo gallbladder were investigated by histochemical methods from days 12–21 of incubation (stages 38–46). On incubation day 14, only neutral mucins were detected; on day 15, neutral and sulfated mucosubstances were observed in the epithelial cells that invaginate the underlying mesenchyme. In the same sites, at day 16 of incubation, neutral, carboxylated and sulfated mucins were seen. From the 17th day of incubation until hatching, neutral, carboxylated and sulfated mucosubstances were present in the surface cells and in the cells lining the epithelial invaginations. During this period, the chemical characteristics of the secretory material are similar to those observed by Yamada and Hoshino (1972) in the fowl.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday     

Histochemistry of mucosubstances in the gallbladder epithelium of the chick embryo

Mucosubstances of epithelial cells of the chick embryo gallbladder were investigated by histochemical methods from days 12-21 of incubation (stages 38-46). On incubation day 14, only neutral mucins were detected; on day 15, neutral and sulfated mucosubstances were observed in the epithelial cells that invaginate the underlying mesenchyme. In the same sites, at day 16 of incubation, neutral, carboxylated and sulfated mucins were seen. From the 17th day of incubation until hatching, neutral, carboxylated and sulfated mucosubstances were present in the surface cells and in the cells lining the epithelial invaginations. During this period, the chemical characteristics of the secretory material are similar to those observed by Yamada and Hoshino (1972) in the fowl.